Magnetic memory element and system



Oct. 16, 1962 F. I .vPosT MAGNETIC MEMORY ELEMENT AND SYSTEM Filed Feb.9, 1956 FIG. 2

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FIG. 4b

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FIG. 40

FIG. 4d

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FIG. 4c

FREDERICK `L. POST MMM AGENT Oct. 16, 1962 F. L. PosT MAGNETIC MEMORY`ELEMENT AND SYSTEM 5 Sheets-Sheet 2 Filed Feb. 9, 1956 a/(14% GENT vOct. 16, 1962 F. l.. Pos1" MAGNETIC MEMORY ELEMENT AND SYSTEM 3Sheets-Sheet 3 Filed Feb. 9, 1956 SET-UP x DRIVER RESTORE x DRIV ER R EESI NW EL SP M A @ZEOOMQ x COORDINATE WRITE-ERASE DRIVER INVENTOR.FREDERICK L. POST MATRIX DECODING AGENT United States Patent "ice3,059,224 Y MAGNETIC MEMGRY ELEMENT AND SYSTEM Frederick L. Post,Poughkeepsie, N.Y., assignor to International Business MachinesCorporation, New York, N.Y., a corporation of New York Filed Feb. 9,1956, Ser. No. 564,530 17 Claims. (Cl. 340-174) This invention relatesto magnetic memory devices and, more particularly, to improvements insuch devices and in their use with magnetic core memory systems, such asdescribed in the copending United United Stat-es patent application,Serial No. 556,289, filed December Z9, 1955, now abandoned, to whichthis application is related as a continuation in part.

Memory components employing magnetic core storage elements are known inthe prior art, with access to information stored therein attained atrandom addresses through the use of multiple coincidence of currentpulses in employment of the principle that the response of a lmagneticcore having a substantially rectangular hysteresis loop is highlynon-linear. Most systems of this type consist basically of a coordinatearray of cores threaded by a grid of horizontal and vertical selectionwinding wires. Each core is maintained in one of its two remanentmagnetic states, which arbitrarily are designated to represent binary land 0, with information stored in a given core by delivery of a currentpulse on a selected hori- Zontal lwinding and a further current pulse ona selected vertical winding. The pulse polarity and windings arearranged so that the effects of both are additive only in a single core.The magnetomotive force provided by a single coordinate winding pulse isone half H, where H exceeds the threshold force of the magnetic core butis less than twice the threshold force. Only the single core that isacted upon by both the energized windings receives a force sufficientlygreat to change the established remanence state, provided the pulses areadditive and in proper direction. The other cores linked by one or theother of the selected coordinate windings receive a one half H force andare not appreciably affected. Reading, or transmitting the stored binaryinformation is performed in a similar manner but with the direction ofthe pulses applied to the selected horizontal and vertical windings inan opposite sense to that used for writing and a voltage is developed ina sense winding which links each of the cores in the coordinate plane,provided a change in state occurs in the interrogated core in thatplane. This mode of transmission is destructive as reading restores thecores to a binary zero or datum state.

A major difficulty encountered in coincident current type of operationis that the. current pulses applied to each selection winding both forwriting and reading operations must be accurately controlled and lessthan the threshold, force by a predetermined amount depending upon thesquareness of the hysteresis loop of the cores involved. Even with suchvcontrol, when the drive pulses are actually terminated the half selectedcores do not return to the same magnetic position as before andsuccessive read and write direction pulses cause excursions of minorhysteresisloopsin an effect known to the art as the delta effect andwhich causes partial signals and non-uniform signals to obscure theoutput. lFurther, and particularly in reading the stored information,the inability to increase the current magnitude on each coordinateselection line of such an array limits the speed with which the coresmay be switched from one state to another because of these effects andthe inherent threshold characteristic.

A recently devised system that avoids dependence upon the thresholdcoercive force in magnetic cores and thus allows higher speed operationwith driving currents of 3,059,224 Patented Oct. 16, 1962 greatermagnitude is described and claimed in the copending application of L. P.Hunter, Serial No. 546,180, led November 10, 1955, now Patent Number2,869,112, which application is assigned to the same assignee. Thisapplication is incorporated herein as part of the disclosure byreference hereto. ln this system, a multipath magnetic memory element isemployed having a pair of input legs and a pair of output legs.Coincident application of an input pulse to a winding on each of theinput legs is required to write and read by changing the direction offlux through the entire magnetic body to a clockwise or counterclockwisedirection. When an input pulse is applied to a single input leg winding,no significant flux change occurs in one of the output legs about whichthe sense winding is Wound. In this system read and write current pulsesapplied to the input windings may be of any -desired magnitude above apredetermined minimum and high speed operation is attained but arelatively large volume of magnetic material is switched Afrom oneremanence direction to the other and the drive pulse energy -required isnecessarily large.

An improved storage element and system is provided in accordance withthe present invention wherein the flux direction throughout the greaterpart of the element remains constant at least during a sensing operationso that less driving power is required and still higher speeds ofoperation are attainable.

One form of the improved device is particularly adapted for high speedoperation with information stored without dependence upon flux directionor in other words without distinguishing between binary one and binaryzero through the opposite remanence states of the material. The deviceis provided with a pair of flux paths wherein the condition that fluxtraverses one path represents binary one and that flux traverses theother path represents binary zero where the total flux available in themember is restricted to an amount sucient to be accommodated by one pathto the exclusion of the other. Means are `provided to force the flux toenter one or the other path and reading is accomplished, for exam-ple,by causingv the flux to traverse a particular path about which a sense.winding is positioned. If the flux is already contained in that paththere is no output developed Whereas if the flux is caused to enter thatpath the uX change induces a signal voltage. i

The means for switching the flux from one path to the other operatesindependently of a coercive force threshold with respect to the maincore body and the hysteresis characteristic of the magnetic materialneed not have sharply defined knees, Further, the switching means mayoperate at high speeds and without a maximum limitation in currentmagnitudes employed.

A further form of the improved memory element and operating technique isadapted for use in non-destructive sensing systems. In this form,information storage is dependent upon relative flux directions ratherthan the presence or absence of flux in a particular alternate flux pathbut the pair of output paths are provided with the flux shifted from oneto the other in sensing. The ux direction remains unchanged by theswitching operation and a transfer back and forth from one leg to theother may be made repeatedly without loss of the information.

An object of the invention is to provide an improved magnetic memoryelement.

Another object of the invention is t'o provide a magnetic memory clementwherein information stored as a ilux condition is detected by shiftingthe flux between alternate ux paths.

A further object is to provide a memory system employing magneticelements having a pair of alternate flux paths with binary informationrepresented by the presence of 'llux in one or the other of the paths.

A broad object of the invention is to provide a magnetic memory devicecapable of high speed operation.

Yet another object is to provide an improved pulse transfer controllingdevice.

Still another object of the invention is to provide a magnetic corememory element and system adapted to store information and deliver anindication of its storage condition non-destructively.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of example, the principle of the invention andthe best mode, which has been contemplated, of applying that principle.

In the drawings:

FIGURE l is a diagrammatic View of one form of the invention wherein atoroidal magnetic core is provided with a portion thereof subdividedinto two parallel ux paths.

FIGURE 2 represents a modication in the structural form of the basicmemory element.

FIGURE 3 illustrates a further modification wherein the arrangement ofwindings associated with the parallel iiux paths is shown in differentform.

FIGURES 4a to 4d comprise diagrams of the memory element wherein certainflux paths are illustrated as used in explaining the operation and useof the device.

FIGURE 5 illustrates one form of the memory element as a pulse transferdevice employed as a shifting register component.

FIGURE 6 is a diagram of a multipath magnetic structure adapted for useas a non-destructive memory element.

FIGURE 7 represents a modification in the form of the device shown inFIGURE 6.

FIGURE 8 is a representation of one plane of a three dimensional arrayof magnetic elements operable in accordance with the improvednon-destructive sensing technique.

The basic structure of the magnetic storage element may comprise atoroidal core 10 as shown in FIGURE 1 having an aperture 12 positionedwithin the principal ilux path so as to divide one portion of the coreinto two parallel sections A and B of substantially equal crosssectionalarea immediately adjacent one another. The cross section of magneticmaterial in each of these sections may be equal to or somewhat greaterthan that in a further portion of the core 10 designated as section C.The opening 12 may be drilled or otherwise formed and may be positionedparallel to the axis of the core as shown or in a radial direction or atany selected angle intermediate these extremes provided the ux paths Aand B are substantially equal and separate from one another. Obviouslythe form of the core need not be toroidal and rectangular and othercongurations of both core and openings are contemplated so as to beconsidered within the scope of the present description and claims. Amodiiied structure is shown for example in FIGURE 2 wherein the openingsand windings t-o be described are given designations similar to thoseused in FIGURE 1.

Referring again to FIGURE 1, the toroidal core 10 is provided with afirst winding 14 linking the outer core section B through the opening 12and through an additional opening 16 intermediate the opening 12 and theouter periphery of the core. A second winding 18 links the inner coresection A through the opening 12 and a further opening 20 intermediatethe opening 12 and the inner periphery of the core. The windings 14 and18 are illustrated as single turn igure eight loops but may compriseplural turns if so desired, poled in any desired manner, or may takeother forms as described hereafter.

Section C of the core 10 is also provided with a winding 22 that may bepulsed to establish a remanent flux in the core. In the first embodimentto be described the direction of remanence flux established initially isimmaterial and having been established the winding 22 is no longeremployed.

The invention is based upon the phenomenon that a localized flux isestablished in sections A and B of the core 10 and circulates about theopenings 16 and 20 when the windings 14 and 13, respectively are pulsed.Establishment of this localized flux path results in saturation of theassociated one of the pair of paths A or B so that the iiux in theprincipal body of the core is forced to complete its circuit through theother path. Experimental data leads to the conclusion that the localizedflux path established as a result of pulsing one or the -other of thewindings 14 or 18 is somewhat parabolic in shape and symmetrical aboutthe opening 16 or 20 and, since the path around the core through theother legs is longer, it remains localized. The etects of a localizediiux of this kind is described more fully in the copending application,Serial Number 530,523, iield August 25, 1955, now abandoned, on behalfof E. A. Brown and R. C. Lamy, which application is assigned to the sameassignee.

The :structure may be modified in form but it is preferable thatsections A and B are generally of equal crosssectional area and areindividually greater than the section C so that the initial iiux may beestablished in the core by pulsing the winding 22 with a current of anydesired magnitude. In this case, section C is saturated and the maximumflux established in the core is limited regardless of the pulsemagnitude and the remanent iiux resulting may be fully accommodated byeither one of the sections A or B. On the other hand, the leg C may beof greater cross-section but with the energy supplied to winding 22limited to an amount producing such-a limited iiux density. Further, thesections A and B may be of unequal cross-section, however, each must beable to accommodate all the tiux set up in the core without reachingsaturation.

Referring to FIGURE 3, a modified form of the windings 14 and 18 isillustrated wherein a localized liux circulation is established in pathsA and B in a manner similar to that employed in the copendingapplication of E. A. Brown, Serial No. 383,568, tiled October l, 1953,now Patent Number 2,902,676. It is also contemplated that a localizediiux may be established through use of a winding through a single hole,as disclosed in the above referred to application, provided the polarityof the control signals are proper.

Pulsing the winding 22 in the structures shown in FIGURES 1, 2 or 3results in establishment of a flux pattern in one or the other directionaround the main magnetic circuit and a clockwise circulation isillustrated as an example in FIGURE 4a. As shown in this figure the iiuxdivides substantially equally through both sections A and B. Section Cmay be initially saturated by the current applied to windings 22 asmentioned heretofore but sections A and B may not be saturated due totheir larger individual cross-sectional area.

With a current pulse applied to the winding 14 associated with sectionB, its eiective reluctance increases and the main iiux traversing thispath is switched to section A as shown in FIGURE 4b. The fluxcirculation around the opening 16 is shown to be clockwise in direction,howeven'it may be counterclockwise with the same overall result withrespect to which one of the paths A or B is traversed by all of the mainflux. With a current pulse applied thereafter to the winding 18, theregion around the opening k2) is locally saturated and all of the mainilux switches from section A to section B as shown in FIGURE 4c, wherethe pulse applied to winding 18 is of one polarity.

The pulse polarity applied to the windings 14 and 18 is immaterial incausing the switching action as only the direction of localized fluxaround the associated opening is changed, however other eiects areproduced which control the polarity of the output signal as will bedescribed later.

In using the basic memory device thus far described both for high speedinformation entry and transmission,

the winding 18 may perform the function of read and write zero while thewinding 14 performs the function of sense and write one. As mentionedbefore, storage is independent of flux direction and flux traversing thepath B is assumed to represent a datum condition Vor binary zero by thestated functions assigned to the windings.

The datum condition (FIGURE 4c) is established by pulsing winding 18 andthereafter a Zero is written either by again pulsing 18 or by failing todo so; in either case the flux pattern remains unchanged with all theflux traversing path B. A binary one is written by pulsing winding 14 toestablish the ux path through section A (FIGURE 4b). Reading shifts anyliux in sect-ion A to section B and is destructive in that the datumcondition is reestablished by reading. If a one condition had beenestablished by pulsing the winding 14 in the polarity shown in FIGURE4d, the main flux is switched to section A and a localized ux isestablished around the hole 16 in the counterclockwise direction. Thislocalized flux around the hole 16 retains this remanent sense when thepulse on windingr 14 is terminated. 'Ihereafter winding 18 may be pulsedto read the information and increases the reluctance of path A causingthe main iux to return to path B. For the main ux direction shown,clockwise, only a small portion of this main tiux can passintermediatethe hole 12 and hole 16 as this subsection is at remanencein a downward direction and may only saturate. The subsection betweenhole 16 and the outer edge of the core, however, reverses direction andthis right hand half of the ligure eight loop 14 has a voltage pulseinduced in it with the lower winding terminal as shown in the drawingmade positive. With a reversal of polarity of the write one pulsepreviously applied to 14, the polarity of the output signal representingone also is reversed and further, with the same polarity write one pulseused and the original ilux direction established as counter clockwiserather than clockwise, the output signal polarity is also reversed.Therefore, dependent upon the polarity of the write one pulse, either apositive or negative signal may indicate storage of a'binary one and nooutput signal indicates storage of a binary zero.

The output polarity may be made independent of the polarity of the writeone signal by providing an independent sense winding 24 which links theentire section B through the opening 12 as shown in FIGURE 4d. The sensewinding may also be threaded through the hole 16 so as to link only theinner or outer portion of section B, for example a winding 24s, and thusbe made sensitive to` one or the other polarity of the write one signalexclusively. Further, while delivery of an output signal has beendescribed as occurring when flux is caused to enter the section B, itobviously lmay be at other times and gated by appropriate circuitry aswhen the tiux decreases in section B or, either increases or decreasesin section A. l

The magnitude of the read and write current pulses need not be limitedin this arrangement so that high operating speeds may be achieved. Thedevice may also be used in a coordinate matrix array with two readwindings 18 and two write windings 14 employed, one for each dimension,as a threshold exists in the minimum current required to cause a shiftin the main flux from path A to B or vice versa and one unit of currentmay be applied without a significant output developed. In such anarrangement a signal to noise ratio of nine to one has been achieved.Further, an inhibit winding may be used in` opposition to one of thepair of write one windings to form a three dimensional array inaccordance with conventional practice. t

The primary advantages of the novel memory element resides in theextremely high speed operation attainable and the lack of dependenceupon the threshold characteristieV of the core square loop magneticmaterial, provided the remanence to saturation tlux density ratio isgood.

The pulse transfer controlling aspects of the device are demonstrated bymeans of a shift register shown in FIG- URE 5. Here four cores 10-1 to10-4 are interconnected with a separate sense winding 24 for each unithaving one terminal connected to the write one winding 14 of the nextsucceeding core through a diode 26 that is poled to prevent current iiowwhen flux is transferred from section B to section A as a one is enteredin the associated core. The polarity of this diode may be reversed fromthat shown, with the polanity of the winding 14 or its input connectionreversed as discussed previously with respect to sense winding signalpolarity conditions. The other terminals of the sense windings 24 areconnected to a lead 27 that is coupled to ground through a commonresistor R which functions to prevent back transfer of informationpulses in the manner described in the copending application, Serial No.430,059, tiled May 17, 1954, on behalf of M. K. Haynes and now issued asPatent Number 2,881,413.

The cores 1-0-1 and i103 have their windings 1S energized in series froma first shift pulse generator S1 and the cores 10-2 and '10-4 have theirwindings 18 energized from a further shift pulse generator S2, thesegenerators being capable of delivery alternately in time. Now assuming aone is established in core lil-41 as by pulsing its input write oneterminal 28-1 and all the remaining cores store a Zero, core lil-1 hasits ilux passing section A and the flux in core l10-2 to -10-4 have uxpassing section B. As the generator S1 operates and winding '18 of coreslil-1 and .l0-3 is pulsed, no flux change occurs in core lil-3 as thereis no flux to be shifted from section A but such a shift to section Boccurs in core 16-1. This causes a signal to be produced on winding 24of core 1G41 that passes the diode 26 and pulses the write one winding14 of core 1tl-2, shifting the flux in that core to section A. Thissignal pulse iiows through the winding 14-2 and completes its path tothe output winding 244 through the resistor R and lead 27, developing avoltage drop across the resistor R of such polarity as to oppose currentflow caused by the flux change in core 24-1 developing a voltage acrossthe winding `14H1 tending to send current in retrograde through theoutput winding of the preceding core. A subsequent pulse from thegenerator S2 shifts the iiux in this core 1u-2 back to section B anddevelops an output to drive core 1G43 and so on with each core insuccession. A single binary one may be circulated as described or apattern of ones and zeros circulated as established in the cores throughpulsing selected ones of the input terminals 28. yIn this manner, forexample, the register may serve to convert information in parallel formto serial form or vice versa. It is contemplated that a windingcomparable to winding 22 in FIGURES 1 to 3 also be provided on the coresin this arrangement and pulsed simultaneously with the winding 18 forthe associated core so as to momentarily increase the -iiux density atthe time of the shift to increase the volt-time product of the output.

l A device essentially of the same vconstruction as that described butadapted for non-destructive sensing of its magnetic storage condition isshown in FIGURE 6. Here storage is dependent upon the ux directionrather than its presence invoneV of the short parallel paths A or B. Apair of input windings 30 and32 are provided about section C or the corewhich windings are adapted to be pulsed to establish a flux directionrepresentative of binary "land 0, respectively. Obviously a singlewinding may be used to generate opposed flux directions with applicationof opposite polarity signals. Windings 34 and 36 or 36s are providedon-section B and winding 38 on section A, corresponding with thewindings 14, 24 or 24s and 18 in the previous embodiment. The winding 34is termed a set up winding and drives the flux in the main core body outof section Band into section A while winding I38 is Vtermed a readwinding and drives the linx out of section A and into section B andwinding 36 is a sense winding.

Initially the winding 30 or -32 is pulsed to establish the informationrepresenting remanence direction, then the set up winding 34 is pulsedwith a current in either polarity to drive all this ux into section A.To read, the Winding 38 is pulsed, also with current of either polarity,and the flux in section A is driven back into section B where theincrease in flux causes an output voltage to develop in winding 36. Thepolarity of the voltage developed in winding 36 is dependent upon the uxdirection and consequently the storage of ones and zeros may bedistinguished. The set up Winding 34 may again be pulsed and a furtherread operation will once more deliver the information as the establishedllux direction is not destroyed with repeated reading.

Such a non-destructive memory element may be adapted for use in two orthree dimensional arrays by providing a further figure eight orequivalent winding, such as that shown in FIGURE 3 for example andrequiring a minimum of three holes in each path, operable on the iluxpath A and employing a pair of input windings of like polarity forpulsing section C in coordinate fashion as in a coincident currentsystem. A structure having this additional winding on section A is shownin FIGURE 7 where a figure eight winding 40 is provided along with apair of windings 42x and 42y that embrace the input section C. A twodimensional system using the structure of FIGURE 7 as the storageelement is shown in FIG- URE 8 where a plurality of elements 10 arearranged in coordinate columns and rows as in a conventional array andconsidered as one plane of a three dimensional system wherein aplurality of like two dimensional arrays or Z planes are arranged sothat the X and Y coordinate .windings link cores in each Z plane inseries. In this arrangement selection of a particular X and a particularY winding address in coincidence may saturate the section C of a likepositioned core in each of the Z planes to establish one or the otherflux direction. The X, Y address leads 42x and 42y then select a multbitbinary word composed of these several like positioned cores for writingand erasing. A unipolar sense winding s is provided coupled to the sensewindings 36 and is individual to each such Z plane so that when a wordis read out of the array each bit signal is delivered in parallel to thesense winding for that plane and may be a zero or a one as indicated byits polarity. To write a word in such an array write address lines 42xand 42y are pulsed in a vpositive or write 1 sense and each core in theword line tends to store a "1 unless an inhibit winding Z for a bitposition plane is energized. In this manner the zero bits of a binaryword are entered by counteracting the magnetomotive force effect ofeither one of these windings in that plane.

Coincidence of two input write signals is required to set ,up aremanence flux direction in the core body of a selected element andoperation of the system will be explained considering entry of a one inthe core 10 located at the ,upper left hand corner of the array. Theaddress registers 48x and 48y select this address and, through thedecoding matrices 45 and drivers 46, line 42x-'1 and 42y-1 are pulsed ina like sense. Both pulses act on the single core selected and set up ailux direction assumed to be clockwise and representing a binary onestate. To erase this information bit the drivers 46x and 46y may becontrolled to pulse these lines simultaneously in an opposite sense andreestablish a zero ux direction. Proceeding from the condition that aone state is stored in the addressed core it may also be assumed thatthe remaining cores have either a zero or one condition or iluxdirection established in them. To read this information from the array,the Y coordinate read driver 50 is iirst operated to pulse the leads38-'1 to 38-6 and energize lthe windings 38 on each core driving theportion of ux established in the cores, regardless of its direction, outof section A and into section B of each core. Following this operation,to read the information in the particular core selected, a set up driver52 is operated to pulse the line 34-1 energizing the windings 34 of eachcore in the selected x coordinate direction particular to the address ofthe selected core. This causes the tlux in the cores of this selectedrow to switch from section B back to section A. Thereafter the ycoordinate read driver 50 is operated to pulse the line 38-1 energizingthe windings 38 of the cores in the selected y coordinate directionparticular to the address of the selected core. This switches the ux insection A back to section B only in the addressed core and a signal isdeveloped on the winding 36 and sense line s with a polarity indicativeof the flux sense in the core, which signal is amplified by a device5'1. None of the other cores in the addressed y column produce anyoutput as the ux in these cores is already in section B.

Following this reading, a restore driver S4 may be operated to pulse`the lead 40-1 and restore the flux in the non-selected cores of theaddressed row back to section B before proceeding to read at anotheraddress. The information from the same core may be repeatedly read out,however, by again operating the set up driver 52 and pulsing the line34-1 to restore the flux in the addressed core to section A so that asubsequent operation of the read driver 50 to energize lead 38-1 willagain transmit the information held by the addressed core. If desired,the restore driver 54 may be eliminated and the flux in the non-selectedcores restored to section B or unset by operating the read driver 50 topulse the windings 38 in all columns and blocking a gate in the sensewinding circuit at this time. This alternative mode of operation is notas rapid, however, as the restore driver may be operated at the sametime as the set up driver 52 in preparing a further core for reading inthe illustrated arrangement.

The system shown in FIGURE 8 may be further modifled by employment ofsense windings linking only the outer portion of section B of each core,such as the windings 36s illustrated in FIGURE 6. With this arrangementa bipolar sense Winding circuit configuration may be used and moreeifective noise cancellation obtained as a binary one flux condition maybe indicated by a relatively large output voltage and a binary zerocondition by a small output voltage rather than by the relative polarityof signals.

The drivers, decoders and registers shown in block diagram form inFIGURE 8 may be conventional components known to the art. The addressselecting systems 45 may be in the form of a crystal diode matrix, for

example. The drivers 46 may comprise magnetic cores as shown in thecopending application, Serial Number 440,983, tiled July 2, 1954, onbehalf of R. G. Counihan, now Patent No. 2,902,677, dated September 1,1959, or transistors as shown in application, Serial Number 511,082entitled Transistor Amplifiers, filed May 25, 1952, on behalf of J. B.Mackay et al., now Patent No. 2,990,539, dated June 27, 1959.

While there have `been shown and described and pointed out thefundamental novel features of the invention as applied to a preferredembodiment, it will be understood ythat various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in the artwithout departing from the spirit of the invention. It is the intentiontherefore, to be limited only as indicated by the following claims.

What is claimed is:

l. A magnetic core memory device comprising a closed magnetic circuitcapable of assuming stable remanence conditions and having a portionthereof divided into two parallel ilux paths, means for establishing aremanence flux in said magnetic circuit, a separate winding inductivelyassociated with each of said flux paths and operable to increase thereluctance to the ilow of said remanence ilux therein when energized,and means for selectively energizing said windings to cause saidremanence flux to traverse a selected one of said parallel flux paths.

2. A magnetic core memory device comprising a closed magnetic circuitcapable of assuming stable remanence conditions and having `a portionthereof'di'vided into two parallel flux paths, means for establishing aremanence ilux in said magnetic circuit of a density that may beaccommodated by either one of said parallel flux paths without causingsaturation therein, separate winding means inductively associated witheach of said tiux paths and operable to increase the reluetancevto theilow of said remanent flux therein when energized, and means forselectively energizing said winding means to cause said remanent flux totraverse a selected one of said parallel flux paths.

3. A magnetic core memory device as set -forth in claim 2 includingmeans for detecting a shift in ux from one of said parallel paths to theother.

4. A magnetic core memory device compri-sing a closed magnetic circuitcapable of assuming stable remanence conditions and having a portiondivided into two parallel flux paths, means for establishing a remanenceux in said magnetic circuit of a density that may be accommodated byeither one of said flux paths without causing saturation therein, aseparate winding inductively associated with each of said iiux paths andoperable to cause a localized flux circulation confined within theassociated path when energized and thereby increase the reluctance ofthat path to the ow of said remanence ux, means for selectivelyenergizing said windings to cause said remanence ux to traverse aselected one of said parallel paths, yand means for detecting a shift ofsaid remanence flux from lone path to another.

5; A magnetic core memory device as set forth in claim 4 wherein saidmeans for establishing a remanence flux in said magnetic circuitVcomprises a winding embracing a portion of said magnetic circuitseparate from said parallel paths, said portion having a cross sectionalarea less than that of either yone of said parallel paths.

6. A binary storage device comprising a magnetic circuit capable ofassuming stable remanence conditions and having a portion thereofdivided into two parallel flux paths wherein the condition of fluxtraversing one of said paths represents binary one information and thecondition of flux traversing the other of said paths represents binaryzero information, means for establishing a remanence ux in said magneticcircuit, separate winding means inductively coupled with each of saidparallel flux paths and adapted to increase the reluctance of theassociated path when energized and force the remanence ux established insaid magnetic circuit to traverse the other of said paths, means forselectively energizing said windings to establish an informationcondition, and means for subsequentlyv detecting the conditionestablished.

7. A binary storage device as set forth in claim 6 wherein said meansfor establishing a remanence ux in said magnetic circuit comprises awinding embracing the portion of said magnetic core apart from saidparallel ux paths, said portion having a cross sectional area less thanthat of either of said two parallel paths.

8. A binary storage device as set `forth in claim 7 wherein said windingmeans associated with each of said parallel iiux paths is adapted toproduce a localized ux circulation confined within the respective onesof said paths when energized.

9. A binary storage device as set forth in claim 8 wherein saidv windingmeans comprise figure eight windings embracing each of said parallelpaths individually through openings through said parallel pathssubstantially on the center line thereof.

l0. A binary storage device comprising a magnetic circuit capable ofassuming stable rem-anence conditions and having a portion divided intotwo parallel flux paths wherein the,- condition of ilux traversing atleast `one of said paths in one direction represents binary oneinformation and in the other direction represents binary zeroinformation, separate winding means inductively coupled with each ofsaid paths and adapted when energized to increase the effectivereluctance of the associated path and cause the remanence fluxestablished in said `magnetic circuit to traverse'the other of saidpaths, means for establishing an information representing remanence iiuxdirection in said magnetic circuit wherein the remanence flux may beaccommodated in either one of said parallel paths without saturation,and means for subsequentlyenergizing said winding means tonon-destructively determine the iiux direction established.

ll. A binary storage device comprising a magnetic circuit capable ofassuming stabile remanence conditions and having a portion divided intotwo parallel ux paths wherein the condition of flux traversing at leastone of said paths in one direction represents binary one information andin the other direction represents binary zero information, means forestablishing an information representing remanence flux in said magneticcore comprising a winding embracing a portion of said circuit separatefrom said parallel paths, said portion having a cross sectional arealess than that of either one of said two paths, a separate controlwinding inductively coupled with each of said paths and adapted to causea localized linx circulation contined within the associated path` whenenergized and thereby increase the reluctance thereof to ow of saidinformation representing Iflux, means for energizing said controlwindings in a predetermined sequence lfor non-destructively sensing theinformation representing llux direction established. 12. A binarystorage device comprising a magnetic circuit capable of assuming stableremanence conditions 4and having a portion divided into two parallelflux paths wherein the condition of flux traversing at least one 0f saidpaths in one direction represents binary one information and in theother direction represents binary zero information, means forestablishing a remanence flux in `said magnetic circuit of a desireddirection having a density such that it may be accommodated by eitherone of -said parallel ux paths'without saturation, individual controlwinding means inductively coupled with each of said parallel paths andcomprising figure eight winding loops passing through an openingdividing said paths into sub-sections of substantially equal crosssectional area, means for selectively energizing said control windingsto cause a localized flux circulation about said openings and confinedwithin the associated path, output Winding means inductively associatedwith one of said paths, said control winding associated with said onepath being operable -to transfer ux to the other of said paths and thecontrol winding means associated with the other of said paths beingoperable to -shift the ux in the other of said paths to said one path,change in flux in said other path being effective to develop a voltagein said output winding, said voltage polarity being indicative of thebinary information stored.

13. In a magnetic memory array, a plurality of binary storage devicescapable of assuming stable remanence conditions and arranged incoordinate rows and columns, each said storage device having a iirst andsecond portion wherein said second portion is divided in two parallelflux paths each having a cross sectional area at least equal to that ofsaid first portion, input winding means associated with said rstportion, circuit means connecting an input winding means of each saiddevice in each individual column and each individual row, means forenergizing said circuit Imeans for a selected row and a selected columnin coincidence to establish a ux condition in the addressed devicerepresentative of binary information by its direction, individualcontrol winding means inductively associated with the parallel fluxpaths of each said storage device, the control windings in one of saidpaths being series connected along said rows and the control windingmeans for the other of saidpath being series connected along saidcolumn, a sense winding individual to said one of said parallel paths,circuit means connecting said sense windings of said plurality ofstorage devices in series, means for energizing the control windingcircuit corresponding to a selected one of said rows, means forenergizing the control winding circuit corresponding to a selected oneof said columns and causing an output signal to develop in said sensewinding corresponding to the information stored in the storage devicelocated in that row and column.

14. In a magnetic memory array as set forth in claim 13 wherein saidcontrol winding means individual to said parallel flux paths compriseligure eight windings passing through an opening dividing each saidparallel path into subsections of substantially equal cross-sectionalarea, and said sense winding individual to one of said parallel fluxpaths embraces only one of said sub-sections.

15. In a magnetic memory array as set forth in claim 14 wherein saidcircuit means connecting said sense Windings of said plurality ofstorage devices in series connects half said sense windings in onepolarity sense and the other half in the opposite polarity sense.

116. A pulse transfer controlling device comprising a magnetic coredefining a closed flux path of magnetic material capable of attainingone or the other stable residual state, a rst opening positioned throughsaid ux path so as to provide parallel sections of substantially equalcross sectional area, a further opening positioned through each of saidparallel sections to provide sub-sections likewise of substantiallyequal cross sectional area, winding means individual to each of saidsections and passing through said further openings in gure eightfashion, an output winding positioned through said rst opening andembracing one of said parallel sections, means for establishing aremanence ilux condition in a desired one of said stable states whereinthe flux density provided is insuicient to saturate one of said sectionsalone, and means for energizing said winding means for producing anoutput voltage as lux is shifted -to one of said sections, the polarityof said 12 output voltage being indicative of the residual stateestablished.

17. A pulse transfer controlling device comprising a magnetic coredefining a closed magnetic circuit of a material capable of attainingone or the other stable residual state, a lirst opening positionedthrough said flux path so as to provide parallel sections ofsubstantially equal crosssectional arca, a further opening positionedthrough each of said parallel sections so as to provide sub-sectionslikewise of substantially equal cross-sectional area, control windingmeans individual to each of said sections and passing said further.openings in figure eight fashion, an output winding positioned throughsaid further opening of one of said parallel sections and embracing onlyone of said sub-sections, means for establishing a remanence iluxcondition in said magnetic circuit in a desired one of said stablestates ywherein the ux density is insufficient to saturate one of saidparallel sections alone, and means for energizing said control windingmeans and thereby producing a signal voltage in said output winding assaid remanence flux is shifted from one of said sections to the other.

References Cited in the le of this patent UNITED STATES PATENTS2,519,426 Grant Aug. 22, 1950 2,733,424 Chen Jan. 31, 1956 2,734,184Rajchman Feb. 7, 1956 2,769,163 An Wang Oct. 30, 1956 2,769,968Schultheis Nov. 6, 1956 2,783,456 Steagall Feb. 26, 1957 2,803,812Rajchman Aug. 20, 1957 2,814,792 Lamy Nov. 26, 1957 2,814,794 Bauer Nov.26, 1957 2,818,555 Lo Dec. 31, 1957 2,818,556 Lo Dec. 31, 1957 2,842,755Lamy July 8, 1958 2,869,11112 Hunter Jan. 13, 1959 FOREIGN PATENTS814.455 Great Britain June 3, 1959

